Chapter 24: The Plant Body

Cotyledons

"seed leaves." They start to grow during the embryo's heart stage.

adventitious roots

("arriving from outside") Roots originating from the stem at ground level or below; typical of the fibrous root system of monocots.

root cap

-daughter cells from root apical meristem contribute to it -protects the delicate growing region if the root as it pushes through the soil -secretes a mucopolysaccharide (slime) that acts as a lubricant

What is the first step in the formation of a plant embryo?

A mitotic division of the zygote gives rise to two daughter cells: the apical daughter cell and the basal daughter cell. The apical daughter cell is smaller

Cuticle

A protective extracellular layer made of cutin (a polymer made of long chains of fatty acids), wax, and cell wall polysaccharides.

What is the cork?

A protective tissue composed of cells with thick walls waterproofed with suberin.

What does the cortex do?

A region of ground tissue many cells thick, the cortex is primarily parenchyma cells which are relatively unspecialized and often serve as storage depots.

taproot system

A root system typical of eudicots consisting of a primary root (taproot) that extends downward by tip growth and outward by initiating lateral roots. (contrast with fibrous root system). The taproot itself often functions as a nutrient storage organ, as in carrots, sugar beets, and sweet potato.

fibrous root system

A root system typical of monocots. Composed of numerous thin roots that are all roughly equal in diameter. Many have a large surface area for the absorption of minerals. (contrast with taproot system.

How many cell layers does the epidermis typically consist of?

A single cell layer. Epidermal cells are usually small, too.

vascular bundles

A strand of vascular tissue, including xylem and phloem as well as thick-walled fibers. Arranged along periphery of eudicot stems; scattered throughout monocot stems

What does the high surface area-to-volume and extreme branching of roots allow them to do more efficiently?

Absorb water and mineral nutrients.

prop roots

Adventitious roots in some monocots that function as supports for the shoot.

Leaves

Chief organs of photosynthesis

What is the difference between monocots and eudicots?

Monocots are usually narrow-leaved whereas eudicots are usually broad-leaved.

Are plant cells mostly totipotent, multipotent, or pluripotent? What advantages/disadvantages does this give plants?

Most are totipotent, and the ones that aren't are pluripotent. This makes plants able to repair damage wrought by the environment or by herbivores.

What do leaves arise from?

Nodes on the stem

What 3 cell types does ground tissue contain?

Parenchyma, collenchyma, sclerenchyma

Collenchyma cells

elongated, have thick cell walls, provide support for growing tissues, celery strings

The protoderm gives rise to the _____

epidermis

Growth

increase in body size

secondary growth

increase in thickness. produce secondary tissues

vessel elements

larger diameter than tracheids. they meet end-to-end and partially break down their ends to make an open pipeline for water.

vascular cambium

lateral meristem that gives rise to secondary xylem (wood) and secondary phloem (inner bark)

cork cambium

lateral meristem that gives rise to waxy-walled protective cells which become outer bark.

primary growth

lengthening of roots and shoots and proliferation of new roots and shoots through branching. produces primary tissues

Root Apical Meristem

located at the opposite end of the axis from the shoot apical meristem, it contains undifferentiated cells that will continue to divide to give rise to new organs throughout the plant's life.

Shoot Apical Meristem

located between the cotyledons, it contains undifferentiated cells that will continue to divide to give rise to new organs throughout the plant's life.

Ground tissue system

makes up most of the plant body; is everything in between dermal and vascular systems

Parenchyma cells

most abundant, thin cell walls, perform photosynthesis and store protein & starch

What 3 types of cells does the stele consist of?

pericycle, xylem, and phloem

Which tissue systems do the protoderm, the ground meristem, and the procambium give rise to?

protoderm - dermal tissue system ground meristem - ground tissue system procambium - vascular tissue system

Determination

the commitment or an embryonic cell to its ultimate fate in the organism

zone of cell elongation

the part of a plant root, generally above the zone of cell division, where cells are expanding, primarily in longitudinal direction.

vascular tissue system

the plant's plumbing/transport system (distinguishing feature of vascular plants). consists of Xylem and Phloem.

trachieds

type of xylem cell that are spindle-shaped and have pits, thinner regions in the cell wall through which water can move

Sclerenchyma cells

very thick cell walls reinforced with lignin. most of them die but remain for structural support. there are 2 types of sclerenchyma cells: Fibers, which provide rigid support, and Sclereids, which occur in various shapes.

zone of cell maturation

zone above the zone of cell elongation. it is where the cells differentiate.

zone of cell division

The apical and primary meristems of a plant root; the source of all cells of the root's primary tissues.

What are the different fates of the apical daughter cell and the basal daughter cell?

The apical daughter cell forms into the embryo proper, while the basal daughter cell forms into the suspensor

periderm

The cork cambium, cork, and phelloderm constitute the periderm.

What layer is right next to the epidermis on the inside?

The cortex. The ground meristem gives rise to the cortex

Which small layer is on the innermost side of the cortex? What does this layer do?

The endodermis. The cell walls of the endodermis contain suberin, waterproof substance. This allows it to control movement of water and dissolved mineral ions into the inside of the root.

What is the epidermis?

The epidermis is an outer layer of cells that protect the root and absorb mineral ions and water.

How is the cork formed?

The expanding vascular cambium tissue stretches and breaks the epidermis and the outer layers of the cortex, which ultimately flake away. Tissue derived from the secondary phloem then become the outermost part of the stem. Before the dermal tissues are broken away, however, cells lying near the surface of the secondary phloem begin to divide, forming a cork cambium. This meristematic tissue produces layers of cork.

Morphogenesis

The organization and spatial distribution of cells into tissues and organs

petiole

The part of the leaf that attaches the blade to the stem. In many plants, the leaf blade is held by its petiole at an angle almost perpendicular to the rays of the sun. This orientation, with the leaf surface facing the sun, maximizes the amount of light available for photosynthesis. Some leaves track the sun over the course of the day, moving so that they constantly face it.

bark

The periderm and the secondary phloem - that is, all the tissues external to the vascular cambium.

Which primary meristem gives rise to the stele?

The procambium

What are the names of the 3 primary meristems that the apical meristem produces?

The protoderm, the ground meristem, and the procambium.

What is the phytomer?

The repeating unit between the nodes. It includes the node, the internode, and the axillary bud.

Differentiation

The specialization of the cell

What does the shoot system consist of?

The stems, leaves, and flowers.

What is the suspensor?

The suspensor is a supporting structure. It is long and thin.

What is internal to the endodermis?

The vascular cylinder, or stele.

What do roots do?

They absorb water and dissolved minerals and store the products of photosynthesis.

What is the function of the stems?

They hold and display the leaves to the sun and provide connections for the transport of materials between roots and leaves.

True or false: the shoot apical meristem, like the root apical meristem, forms the protoderm, the ground meristem, and the procambium.

True

Can plants grow throughout their lifetimes?

Yes, plants have apical meristems which are always embryonic.

pith

a region of parenchyma cells in monocots that lies in the center of the root. also found in the stems of eudicots.

indeterminate

able to continue growing indefinitely

companion cells

adjacent to sieve tubes and more metabolically active

What is the difference between apical meristems and lateral meristems?

apical meristems orchestrate primary growth whereas lateral meristems orchestrate secondary growth

sieve tube elements

cells of the phloem that are like vessel elements, which are xylem cells, in that they meet end-to-end. They form sieve tubes that are connected by plasmodesmata.

mesophyll

chloroplast-containing photosynthetic cells in the interior of leaves. Within the mesophyll is a network of air spaces through which CO2 can diffuse to photosynthesizing cells. Mesophyll are supplied with water and minerals vascular veins that branch inside the leaf. these veins also transport the products of photosynthesis.

pericycle

consists of 1 or more layers of parenchyma cells. Has 3 important functions: -It is the tissue within which lateral roots arise -It can contribute to secondary growth by giving rise to lateral meristems that thicken the root -The plasma membranes of its cells contain membrane transport proteins that export nutrient ions into the cells of the xylem.

Phloem

consists of living cells. its purpose is to transport cells from sources (primarily leaves) to sinks (roots, developing parts).

Unlike the growth of roots and stems, the growth of leaves is ______

determinate (finite). Leaves usually stop growing once they reach a predetermined mature size.

xylem

distributes water and mineral ions from roots to all cells. it contains Tracheids and Vessel Elements.

What is the job of the root system?

It anchors the plant in place.

What does the dermal tissue system do?

It forms the epidermis, or outer covering. Some epidermal cells differentiate to form stomata, trichomes, or root hairs.

What are leaf primordia and bud primordia?

Leaf primordia - bulges that form as cells divide on the side of the stem. Leaves arise from them. Bud primordia - from above the bases of the leaf primordia, where they may become new apical meristems.